Replacement tip section for a rotor blade and method of replacing a rotor blade tip section

ABSTRACT

A replacement tip section for a rotor blade, from which a legacy tip section was removed, includes a blade tip portion configured to be attached to an intermediate section of the rotor blade after removal of the legacy section. The intermediate section has a connection feature at an end of the intermediate section to which the blade tip portion is attachable. The replacement tip section includes a transition region configured to be attached to a forward end of the connection feature. The transition region is configured to form a leading edge of the rotor blade and extends from the blade tip portion to form an opening into which the intermediate section is attached. The transition region includes a first end having a first airfoil that conforms to the intermediate section airfoil at the connection feature, and a second end having a second airfoil that conforms to the blade tip portion.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to U.S. Provisional ApplicationSer. No. 62/847,268, filed May 13, 2019, the contents of which areincorporated herein by reference in their entirety.

BACKGROUND

The present disclosure relates to the art of aircraft blades, and moreparticularly, to replacement of blade tip sections of rotor bladeassemblies.

Many modern helicopters and some fixed wing aircraft include rotorblades (e.g., helicopter rotor blades). A typical blade includes a rootsection, an intermediate section and a tip section. In order to improveperformance, a typical approach is to design a new rotor blade. However,while the new rotor blade may achieve the desired performance, thisapproach does not address the utility of legacy rotor blades.

BRIEF DESCRIPTION

According to one or more embodiments, a replacement tip section, for arotor blade from which a legacy tip section was removed, includes ablade tip portion having a first end and an opposing end. The blade tipportion is configured to be attached to an intermediate section of therotor blade after removal of the legacy tip section, and theintermediate section has a connection feature at an end of theintermediate section to which the blade tip portion is attachable. Thereplacement tip section also includes a transition region configured tobe attached to a forward end of the connection feature at an end of theintermediate section, and the transition region is configured to form aleading edge of the rotor blade and extend from the blade tip portion toform an opening into which the intermediate section is attached to thetransition region and the blade tip portion. The transition regionincludes a first end having a first airfoil that conforms to theintermediate section airfoil at the connection feature, and a second endhaving a second airfoil that conforms to the blade tip portion.

According to one or more embodiments, a method of replacing a tipsection of a rotor blade includes removing a legacy tip section from anend of an intermediate section of the rotor blade to expose a connectionfeature at the end of the intermediate section, and connecting areplacement tip section to the intermediate section. The replacement tipsection includes a blade tip portion having a first end and an opposingend, and a transition region which extends from the blade tip portion toform a leading edge of the rotor blade at the intermediate section.Connecting the replacement tip section includes attaching the transitionregion to a forward end of the connection feature to form the leadingedge at the intermediate section. The transition region includes a firstend having a first airfoil that conforms to an intermediate sectionairfoil at the connection feature, and a second end having a secondairfoil that conforms to the blade tip portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 depicts a rotary wing aircraft in accordance with an exemplaryembodiment;

FIG. 2 depicts an embodiment of a rotor blade assembly having areplaceable tip section;

FIG. 3 depicts the rotor blade assembly of FIG. 2 in a disassembledstate;

FIG. 4 depicts aspects of an embodiment of a rotor blade assembly havinga replacement tip attached thereto;

FIG. 5 depicts an embodiment of a replacement tip section including atransition region and a hybrid region configured to allow for attachmentto an existing (legacy) rotor blade design;

FIG. 6 depicts a plurality of wire frame representations showingairfoils formed by the replacement tip section of FIG. 8;

FIG. 7 depict examples of aspects of a transition region configured tobe attached to a replacement blade tip;

FIG. 8 is a view of a portion of a rotor blade assembly having anexisting tip section, and illustrates axial positions of the replacementtip section of FIGS. 4 and 5 when the existing tip section is replacedwith the replacement tip section of FIGS. 4 and 5;

FIG. 9 depicts aspects of an embodiment of a method of replacing a rotorblade tip section;

FIGS. 10A and B (collectively referred to as FIG. 10) depict aspects ofthe method of FIG. 9;

FIGS. 11A and B (collectively referred to as FIG. 11) depict aspects ofthe method of FIGS. 9 and 10;

FIG. 12A and B (collectively referred to as FIG. 12) depict aspects ofthe method of FIGS. 9-11; and

FIG. 13A, B and C (collectively referred to as FIG. 13) depict aspectsof the method of FIG. 9-12.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

FIG. 1 schematically illustrates an example of a rotary wing aircraft 10having a main rotor assembly 12. The aircraft 10 includes an airframe 14having an extending tail 16 which mounts a tail rotor system 18. Themain rotor assembly 12 includes a plurality of rotor blade assemblies 22mounted to a rotor hub assembly 20. The main rotor assembly 12 is drivenabout an axis of rotation R through a main gearbox by one or moreengines.

Although a particular helicopter configuration is illustrated anddescribed in this example, embodiments described herein are not solimited, and can be utilized in conjunction with any aircraft or vehiclethat utilizes rotor blades. Examples of such aircraft include high speedcompound rotary wing aircrafts with supplemental translational thrustsystems, dual contra-rotating, coaxial rotor system aircrafts,tilt-rotors and tilt-wing aircrafts, vertical takeoff and lift rotarywing aircrafts, and fixed wing aircrafts.

FIGS. 2 and 3 depict an example of a rotor blade assembly 22, whichgenerally includes a root section 26, an intermediate section 28 and atip section 30 arrayed along a rotor blade span. Each rotor bladesection 26, 28 and 30 may define particular airfoil geometries to tailorthe rotor blade aerodynamics to the velocity increase along the rotorblade span. Sections of the rotor blade assembly may have differentairfoil shapes along the length of the rotor blade. As described herein,an “airfoil shape”, or simply “airfoil”, refers to a shape of the bladeor blade section at a given cross section of the rotor blade assembly22. An airfoil may have an upper airfoil and lower airfoil, as discussedfurther below.

The rotor blade assembly 22 may be made from composite materials, orthey made be made from composite materials and metal elements, such asusing composite skin and core for the airfoil shape and a titanium spar.As described herein, a composite component or composite material is acomponent or material made from two or more constituent materials.Examples of composite materials include fiberglass, fiber reinforcedpolymers, composite wood materials, resin systems and others. It isnoted that composite materials, core materials and materials that canmake components or section of a rotor blade assembly are not limited tothose described herein.

In one embodiment, the rotor blade assembly 22 is a UH-60 blade designused in the BLACK HAWK® helicopter manufactured by Sikorsky, a LockheedMartin Company. Other examples include blades manufactured for theSikorsky SH-60/MH-60 SEA HAWK® helicopter, the Sikorsky SH-3 SEA KINGhelicopter and Sikorsky S-61L and S-61N variants.

The tip section 30, in one embodiment, is a legacy tip section that iscurrently used, or was previously used, as part of a rotor bladeassembly. Examples of legacy blade assemblies that may have legacy tipsections include blade assemblies manufactured by Sikorsky and havingSikorsky part numbers 70150-09100-041 and 70150-09100-043, and otherSikorsky blade assemblies having base part number 70150-09100 and/orconfigured for use in UH60 A/L BLACK HAWK helicopters. Other examples ofblade assemblies that may have legacy tip sections include bladeassemblies manufactured by Sikorsky and having Sikorsky part numbers70150-29100-041 and 70150-29100-042, and other Sikorsky blade assemblieshaving base part number 70150-29100 and/or configured for use in SEAHAWK helicopters. Further examples of blade assemblies that may havelegacy tip sections include blade assemblies manufactured by Sikorskyand having Sikorsky base part numbers 65170-11001 and 56115-20101.

As shown in the example of FIGS. 2 and 3, the rotor blade assembly 22may have an anhedral form, in which the tip section 30 and part of theintermediate section 28 have an anhedral or downward angle from thehorizontal portion of the rotor blade assembly 22. However, the rotorblade assembly 22 may have any suitable or desired form, including anon-angled or angled form such as a dihedral, cathedral, gull, bent orother form.

The tip section 30 is attached to the intermediate section 28 by aconnection assembly 32 having one or more connection features. It isnoted that a portion of the intermediate section 28 inboard of theconnection assembly 32 and the tip section 30 may together form a bladetip.

The connection features in this example include components of a mainspar 34, such as a mounting block 36. Additional components include, forexample shims 38 and washers 40 to provide for weight and balancingadjustments. The tip section 30 is attached to the intermediate section28 via screws 42 or other fasteners, which are inserted through holes inthe main spar 34 and holes arrayed along a blade tip portion 44 and aforward tip portion 46 that forms part of the leading edge of the rotorblade assembly 22.

In some cases, it is desirable to replace the tip section 30 with areplacement tip section that has a different configuration than theexisting tip section 30. For example, replacement tip sections may bedesired for replacement that have a more advanced anhedral design forincreasing lift performance capability. However, an availablereplacement tip section design may not transition well with theconnection assembly 32 or other main blade interface. For example,replacement tip sections may have airfoils that are significantlythicker than existing blade airfoils, which can cause fit andperformance issues.

Embodiments described herein include replacement tip sections andconnection assemblies that are configured to facilitate effectiveattachment of replacement tip sections to existing rotor bladeconfigurations. Embodiments described herein also include methods ofattaching replacement tip sections that ensure a smooth transition froman existing blade intermediate section to a replacement tip section.

The tip sections and methods described herein are configured to blend anairfoil of a loft transition region of an intermediate section foroptimal fit and performance The embodiments incorporate blended and/orhybrid airfoil designs that utilize both intermediate section andreplacement tip airfoil properties, resulting in a very smoothcontinuous blade surface, leading edge and trailing edge.

FIG. 4 depicts an embodiment of a rotor blade assembly 22 including anintermediate section 28 and a replacement tip section 50. Theintermediate section 28 extends along a feathering axis F, and thereplacement tip section includes features that extend along a sweep axisS. As shown, an anhedral is formed by part of the intermediate section28 and the replacement tip section 50. The intermediate section 28defines a leading edge 52 and a trailing edge 54. In this embodiment,the intermediate section 28 was originally configured for attachment toan original or previously attached tip section, which was removed andreplaced by the replacement tip section 50.

The rotor blade assembly 22 includes a connection assembly 56 thatprovides a smooth and aerodynamic transition between the intermediatesection 28 and the replacement blade tip section 50. It is noted that aportion of the intermediate section 28, in combination with thereplacement tip section 50, may form a blade tip.

Aspects of the replacement tip section 50 may include components of theconnection assembly 56. In one embodiment, the replacement tip section50 includes a tip portion 58 that has a first end 60 (an outboard end),which may form a round over. An opposing end 62 connects the tip portion58 to a sweep region 64 of the intermediate section 28. As discussedfurther below, the sweep region 64 may be a pre-existing anhedral regionof the intermediate section 28. Alternatively, if the sweep region 64prior to replacement had a different thickness than the replacement tipsection 50, or did not form an anhedral, the sweep region 64 may includeadditional layers of composite material to build up the intermediatesection 28 and the sweep region 64 to transition to the replacement tipsection 50.

The replacement tip section 50 includes a transition region 66 thatextends along a leading edge of the rotor blade assembly 22. Thetransition region 66 has a first end 68 configured to conform to aleading portion of an airfoil at an end of the intermediate section 28,e.g., over the sweep region 64. The transition region 66 has a secondopposing end 70 that forms a leading portion of an airfoil at the end 62of the tip portion 58.

As described herein, conforming the transition region 66 or othercomponent to an airfoil refers to matching the shape of the airfoil sothat a smooth transition can be established. The shape can be matched bymatching various airfoil properties. Examples of such properties includechord length, thickness to chord (t/c) ratio, maximum thickness (MT), ¼chord point, upper and lower MT points, maximum mid thickness point andtwist angle.

In one embodiment, the transition region 66 is configured as a leadingedge cap made from one or more composite skins, which can be bonded tothe sweep region 64, and/or attached in another suitable manner (e.g.,by attaching with mechanical fasteners such as screws or using bothbonding and fasteners). As described below, in one embodiment, the sweepregion 64 is formed by bonding one or more upper and lower compositeskin layers that can be bonded onto pre-existing composite skins of thesweep region 64 and/or other portions of the intermediate section 28.

FIGS. 5 and 6 show an embodiment of a replacement tip section 71, whichincludes a swept tip portion 72, an end portion 74 at an outboard end ofthe replacement tip section 71 (forming, e.g., a round over), atransition region 76 (which may be similar to the transition region 66),and a hybrid region 78, and illustrates airfoil properties thereof. Inthis embodiment, the transition region 76 extends from an end 80 of theintermediate section 28, which has a first airfoil. The transitionregion 76 forms a leading portion of an airfoil, and transitions to asecond airfoil at a connection point with the hybrid region 78. In oneembodiment, the transition region 76 forms an opening 77 into which theintermediate section 28 can be inserted to attach the transition region66 and the blade tip portion 58 to the intermediate section 28. Thehybrid region 78 in turn has a variable or blended airfoil configurationthat gradually changes to conform to the airfoil at a first end 82 ofthe replacement tip section 71. The replacement tip section 71, in oneembodiment, can be installed onto a rotor blade assembly as a singlepiece.

FIG. 6 illustrates various airfoils at locations or positions along aspan of the replacement tip section 71. It is noted that the airfoilsshown in FIGS. 5 and 6 extend perpendicular or normal to a featheringaxis (e.g., the axis F). The airfoils are not so limited, as some or allof the airfoils may extend along a different axis, such as a sweep axis(e.g., the axis S).

Referring again to FIG. 5, examples of the position or location ofvarious components or portions of the transition region 76, the hybridregion 78 and the replacement tip section 71 are shown relative to ablade span. The locations are shown as lines representing cross-sectionsof the rotor blade assembly 22 in a direction perpendicular or normal tothe feathering axis F. In this embodiment, the transition region 76begins at line A and has an airfoil that conforms to the airfoil at theintermediate section 28. The transition region 76, in one embodiment,forms a curved portion 84 between lines A and B, and further transitionsfrom line B to line C at the beginning of the hybrid region 78.

The hybrid region 78 has a variable airfoil configuration that formsairfoils along the hybrid region that vary so that the shape and size(e.g., chord length, thickness, t/c ratio, etc.) of the hybrid region 78varies from a first airfoil at line C configured to conform to the swepttip portion 72, to a second airfoil at line D configured to conform tothe replacement tip section 71. The swept tip portion extends from lineD to the end portion 74, which extends from line E to line F. As shown,the transition and hybrid regions extending from line A to B and line Bto C comprise only a partial airfoil (i.e., the leading edge of therotor blade), and attach to the existing rotor blade assembly 22 to forma complete airfoil. In contrast, the swept tip portion 72 forms acomplete airfoil which extends from the end of the existing rotor blade.

The portions and regions have selected lengths based on the type ofreplacement blade portion, design and performance considerations andother factors. An example of replacement tip section and intermediatesection dimensions has a distance of about 299 inches (about 7.59meters) from the axis of rotation R of the main rotor assembly. In thisexample, the distance from line A to line B is about one (1) inch (about2.54 centimeters or cm), the distance from line B to line C is about8.68 inches (about 22.05 cm), the distance from line C to line D isabout 1.32 inches (about 3.35 cm), the distance from line D to line E isabout 11 inches (about 27.94 cm), and the distance from line E to line Fis about one (1) inch (about 2.54 cm). The distances in this example arealong a feathering axis extending from the axis of rotation R. It isnoted that this example is not intended to be limiting, as portions ofthe replacement tip section and/or intermediate sections can have anydesired length between the various lines.

As noted above, the transition region 76 may include a curved portion 84that facilitates an aerodynamic shape transition from the end 80 to alocation along the transition region 76. For example, as shown in FIG.7, the curved portion 84 forms a transition S-curve that may havevarious widths and curvatures depending on the configuration of theintermediate section 28 and a replacement tip section.

FIG. 8 is a view of a portion of the rotor blade assembly 22 having anexample of an existing tip section 110, also referred to as a legacy tipsection, and illustrates an example of the axial positions of thereplacement tip section 71 of FIGS. 5 and 6 when the existing tipsection 110 is replaced with the replacement tip section 71. Lines A-Dof FIG. 5 correspond to lines A-D of FIG. 8.

The existing tip section 110 is attached to a sweep portion 112 of theintermediate section 28, and has a leading portion 114, a tip portion116 and an end portion 118 forming a tip round over. FIG. 8 demonstrateshow a replacement tip section such as the replacement tip section 71 canbe installed on an existing intermediate section without requiringsubstantial redesign of the intermediate section.

FIGS. 9-13 illustrate an embodiment of a method of replacing a tipsection of a rotor blade assembly. It is noted that the followingdescription includes a number of method steps or stages. The method maybe performed as described below and include all of the steps or stagesin the order described. The method is not so limited, as the method mayinclude fewer than all of the steps or stages, or may include performingone or more of the steps or stages in a different order than thatdescribed below. The method is described with reference to an example ofan existing flat (non-anhedral) tip section and an anhedral replacementtip section. It is noted that the method is not limited to the followingexample, and may be used with any suitable rotor blade assembly,existing tip section and replacement tip section having any desiredconfiguration.

In a first stage, shown in FIG. 9, an existing or legacy tip section 90is removed from an end of an intermediate section 92 of a rotor bladeassembly. The intermediate section 92 may be the intermediate section ofthe rotor blade assembly 22 of FIG. 1. The intermediate section 92includes a titanium alloy spar 94 on which is attached a mounting block96 originally configured for attachment to the existing tip section 90.The mounting block 96 extends from a portion 98 that is formed from acomposite core and composite skins forming an airfoil. The mountingblock 96 may be aluminum, although other materials (including aluminum,titanium or a composite) may be used. Removal of the existing tipsection 90 includes removing existing fasteners such as screws fromfastening points 100 from holes in the existing tip section 90 and thespar 94.

For example, the intermediate section 92 may be part of one of thelegacy rotor blade assemblies and/or be attached to one of the legacytip sections described as examples above. The existing or legacy tipsection 90, in one example, is attached to a rotor blade assembly for aBLACK HAWK helicopter having a titanium spar manufactured by Sikorsky,such as a spar having Sikorsky base part number 70150-09102 (e.g.,Sikorsky part number 70150-09102-041 or 70150-09102-042). In anotherexample, the existing section 90 is attached to a rotor blade assemblyfor a SEA HAWK helicopter having a titanium spar manufactured bySikorsky, such as a spar having Sikorsky base part number 70150-29002(e.g., a spar having Sikorsky part number 70150-29002-041).

The mounting block 96 may include or be part of an aluminum tip blockmanufactured by Sikorsky and having Sikorsky base part number70150-09133 (e.g., Sikorsky part number 70150-09133-041 or70150-09133-043).

In a second stage, shown in FIG. 10, the mounting block 96 is trimmed sothat the mounting block 96 does not interfere with a replacement tipsection, which may have a different configuration that the existing tipsection. For example, if the replacement tip section forms an anhedral,the mounting block 96 is trimmed so as not to interfere with theanhedral. FIG. 10A shows the mounting block prior to trimming, and FIG.10B shows the mounting block 96 after trimming

In the third stage, shown in FIG. 11, the trailing edge of the portion98 is trimmed to ensure a smooth trailing edge transition and avoidinterfering with the replacement tip section. FIG. 11A shows the portion98 prior to trimming, and FIG. 11B shows the portion 98 after trimming.

In the fourth stage, shown in FIG. 12, new composite skins may be bondedto the remaining surfaces of the anhedral portion to provide a smoothand consistent airfoil shape when a replacement tip section is attached.For example, an upper skin 102 is bonded to an existing upper skin ofthe portion 98, and a lower skin 104 is bonded to an existing lower skinof the portion 98. The upper and lower skins form an airfoil thatconforms to the airfoil shape or at least permits a transition region ofa replacement tip section to be properly positioned at a leading edge.The upper skin 102 and the lower skin 104 may have any number of layersand/or thicknesses to provide a desired transition from the intermediatesection 92. For example, the upper skin 102 and the lower skin 104 mayhave thicknesses and/or thickness variations that correspond to thethickness of the replacement tip section. In addition, if thereplacement tip section is an anhedral tip section, the upper skin 102and/or the lower skin 104 are applied to form an anhedral configuration.However, it is understood that the skins 102 and 104 and the fourthstage need not be used in all aspects, such as if the transition region76 shown in FIG. 5 is shaped to directly attach to the rotor bladeassembly.

In the fifth stage, shown in FIG. 13, a replacement tip section 106(e.g., the replacement tip section 50 or 80) is attached to the modifiedportion 98. The replacement tip section 106 includes a transition region108 is mounted over a forward end of the portion 98 and the upper andlower skins 102 and 104, and the replacement tip section 106 is mountedon the spar 94 and may be attached via screws (e.g., at attachmentpoints 100). It is noted that the replacement tip section 106 (includingthe transition region 108) can be attached to the intermediate section92 as a single piece.

As shown in FIGS. 13B and 13C, the rotor blade assembly exhibits asmooth and aerodynamic transition between the intermediate section andthe replacement tip section.

As demonstrated in FIGS. 9-13, the rotor blade assembly 22 can beconverted to a new tip design using an existing intermediate sectionwithout the need to strip and rebuild or design new components. Thenewly bonded upper and lower skins transition the blade skin, mating anew tip section airfoil shape to the rest of the blade seamlessly.

Embodiments described herein present a number of advantages andtechnical effects. For examples, the embodiments provide systems andmethods that allow for efficient and effective replacement of a tipsection of a rotor blade. Tip section replacement may be performed toimprove aircraft performance, such as lift, hover and/or cruiseperformance A replacement tip section may have different characteristicsthan an existing tip section, which poses significant challenges inreplacement. For example, replacement tips may have differentthicknesses and other airfoil properties that make it difficult totransition from a blade section to a replacement tip section.Embodiments described herein address such challenges and provide ways toreplace tip sections while retaining the desired performance propertiesof the blade, and without the need to redesign an entire blade assembly.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A replacement tip section for a rotor blade fromwhich a legacy tip section was removed, the replacement tip sectioncomprising: a blade tip portion having a first end and an opposing end,the blade tip portion configured to be attached to an intermediatesection of the rotor blade after removal of the legacy tip section, theintermediate section having a connection feature at an end of theintermediate section to which the blade tip portion is attachable; atransition region configured to be attached to a forward end of theconnection feature at an end of the intermediate section, the transitionregion configured to form a leading edge of the rotor blade andextending from the blade tip portion to form an opening into which theintermediate section is attached to the transition region and the bladetip portion, the transition region including a first end having a firstairfoil that conforms to the intermediate section airfoil at theconnection feature, and a second end having a second airfoil thatconforms to the blade tip portion.
 2. The replacement tip section ofclaim 1, wherein the transition region includes a curved portion at theleading edge that transitions the transition region to an intermediatesection leading edge.
 3. The replacement tip section of claim 1, furthercomprising a hybrid region having a leading edge and a trailing edgeconfigured to conform to a corresponding leading edge and acorresponding trailing edge of the blade tip portion.
 4. The replacementtip section of claim 3, wherein the hybrid region forms a variableairfoil that varies from a first airfoil configured to conform to thetransition region to a second airfoil configured to conform to the bladetip portion.
 5. The replacement tip section of claim 3, wherein thehybrid region extends from the transition region to the blade tipportion
 6. The replacement tip section of claim 3, wherein the hybridregion is configured to form a smooth transition of the leading edgefrom the transition region to a sweep zone of the blade tip portion. 7.The replacement tip section of claim 1, wherein the transition region isconfigured to be attached to one or more composite skin layersconfigured to be bonded to pre-existing upper and lower composite skinsof the intermediate section.
 8. The replacement tip section of claim 7,wherein the one or more composite skin layers are configured to bebonded to the connection feature as part of attaching the replacementtip section to the intermediate section, the one or more composite skinlayers forming an airfoil that conforms to the blade tip portion.
 9. Thereplacement tip section of claim 1, wherein the connection featureincludes a component previously configured to connect the intermediatesection to a previously attached tip section, and attaching thetransition region includes modifying the component to adapt thecomponent to permit attachment of the replacement tip section.
 10. Thereplacement tip section of claim 1, wherein the transition region isconfigured to be attached to the intermediate section by existingfastening features.
 11. A method of replacing a tip section of a rotorblade, comprising: removing a legacy tip section from an end of anintermediate section of the rotor blade to expose a connection featureat the end of the intermediate section; and connecting a replacement tipsection to the intermediate section, the replacement tip sectionincluding a blade tip portion having a first end and an opposing end,and a transition region which extends from the blade tip portion to forma leading edge of the rotor blade at the intermedia section, wherein theconnecting includes attaching the transition region to a forward end ofthe connection feature to form the leading edge at the intermediatesection, the transition region including a first end having a firstairfoil that conforms to an intermediate section airfoil at theconnection feature, and a second end having a second airfoil thatconforms to the blade tip portion.
 12. The method of claim 11, whereinthe transition region includes a curved portion at the leading edge thattransitions the transition region to an intermediate section leadingedge.
 13. The method of claim 11, wherein the replacement tip sectionincludes a hybrid region having a leading edge and a trailing edgeconfigured to conform to a corresponding leading edge and acorresponding trailing edge of the blade tip portion.
 14. The method ofclaim 13, wherein the hybrid region forms a variable airfoil that variesfrom a first airfoil configured to conform to the transition region to asecond airfoil configured to conform to the blade tip portion.
 15. Themethod of claim 13, wherein the hybrid region extends from thetransition region to the blade tip portion.
 16. The method of claim 13,wherein the hybrid region is configured to form a smooth transition ofthe leading edge from the transition region to a sweep zone of the bladetip portion.
 17. The method of claim 11, wherein connecting thereplacement tip section includes bonding one or more composite skinlayers to pre-existing upper and lower composite skins of theintermediate section, and attaching the transition region to a forwardend of the one or more composite skin layers, the one or more compositeskin layers forming an airfoil that conforms to the blade tip portion.18. The method of claim 17, wherein connecting the replacement tipsection includes trimming a trailing portion of the intermediate sectionto accommodate the replacement tip section.
 19. The method of claim 11,wherein the connection feature includes a component previouslyconfigured to connect the intermediate section to the legacy tipsection, and attaching the transition region includes modifying thecomponent to adapt the component to permit attachment of the replacementtip section.
 20. The method of claim 11, wherein the transition regionis configured to be attached to the intermediate section by existingfastening features.